Noise suppression method, noise suppression method program, recording medium recording noise suppression method program, and noise suppression apparatus
a noise suppression method and program technology, applied in the field of noise suppression methods, can solve the problems of difficult to ensure the noise reduction effect of a portion in fast motion, and difficulty in sufficiently ensuring the noise reduction effect, so as to shorten the necessary time for convergence, the feedback ratio is gradually increased, and the noise reduction effect is great.
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first embodiment
1. Configuration of Embodiment
[0045]FIG. 1 is a block diagram illustrating a noise filter according to a first embodiment of the present invention. This noise filter 10 is a time-cyclic noise filter, and suppresses noise of an input video signal S1 using the difference between fields or the difference between frames to output an output video signal S2.
[0046]In this noise filter 10, a reference-video-signal generation section 11 delays the output video signal S2 for a period of one field or one frame, and outputs a reference video signal S11. More specifically, the reference-video-signal generation section 11 performs motion compensation on the output video signal S2 to generate the reference video signal S11.
[0047]That is to say, as shown in FIG. 2, in the reference-video-signal generation section 11, a delay-signal generation section 12 delays an output video signal S2 for a period of one field or one frame to generate a delay video signal S12. A motion-vector detection section 13 ...
embodiment
3. Effect of Embodiment
[0079]With the above configuration, it is possible to suppress noise more sufficiently and at a higher speed than in the past by counting the number of fields or the number of frames after a sudden change in the signal level of an input video signal, and dynamically controlling the feedback ratio to the increase gradually in accordance with the count value.
[0080]Also, at this time, a criterion is set to detect an area in which the signal level has changed abruptly on the basis of the measuring result of the noise level. This makes it possible to effectively avoid the erroneous detection of a still-image portion and a moving image portion by the noise level, and to reliably obtain the noise reduction effect.
[0081]Also, the count values of all areas are initialized to 0 by the detection of a scene change. Thus, it is possible to suppress noise more sufficiently and at a higher speed than in the past after a scene change.
[0082]Also, a feedback ratio kc is generat...
second embodiment
[0083]FIG. 9 is a block diagram illustrating the noise filter according to a second embodiment of the present invention. In this noise filter 40, the same components as those in the noise filter 10 of the first embodiment are marked with the corresponding reference numerals, and the duplicated descriptions will be omitted.
[0084]In the noise filter 40, the band division section 41 transforms the difference signal S4, which is a signal in a pixel area, into sub-difference signals S4B having a plurality of bands of the frequency domain, and outputs the signal. Here, various methods, such as an orthogonal transformation processing, for example, Hadamard transformation, Haar transformation, a discrete cosine transformation, etc., a wavelet transformation using a filter bank, sub-band division, etc., can be applied to the transformation processing into the frequency domain.
[0085]In a compensation-signal generation section 42, a amplifier circuit 44 multiplies the sub-difference signals S4...
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